This invention relates to a data input system including a keyboard having no moving parts.
The invention has application, for example, to a non-mechanical, vandal resistant keyboard for use with through-the-wall automated teller machines (ATMs). As is well known, in operation of an ATM a user inserts a customer identifying card into the machine and then enters certain data (such as codes, quantity of currency required or to be paid in, type of transaction, etc.) upon a keyboard associated with the machine. The machine will then process the transaction, update the user's account to reflect the current transaction, dispense cash, when requested, and return the card to the user as part of a routine operation. A through-the-wall ATM is mounted in the wall of a bank or other building, with the keyboard being accessible from outside the building.
Keyboards of through-the-wall ATMs are susceptible to vandalism. Thus, keyboards having movable keys used in such ATMs are vulnerable in that vandals may attempt to render the keys inoperative by, for example, applying glue or other viscous material to the keys or by forcing foreign objects into the key mechanism. Moreover, keyboards having movable keys may be adversely affected by environmental conditions such as rain. In many ATMs, the keyboard is protected by an anti-vandal screen which normally covers the keyboard, but which is automatically withdrawn to expose the keyboard when a customer identifying card is inserted into a card receiving slot of the ATM at the commencement of a customer transaction. The problems referred to above are particularly acute in the case of an ATM which is not provided with an antivandal screen.
A non-mechanical, touch keyboard is known, for example, from U.S. Pat. No. 3372789. This known keyboard comprises a transparent plate provided with touch switches consisting of concave cavities in the plate, each cavity being associated with a photoelectric transducer embedded in the plate which is adapted to be energized by a light beam transmitted across said cavity. This light beam is interrupted by a finger of an operator when the operator touches the concave surface of the cavity, thereby producing an electric control impulse which is used to operate a control device. This known touch keyboard has the disadvantage that, when operating in an unprotected outside environment, moisture and debris can accumulate in the cavities and may give rise to operational errors.
There is also known a capacitive touch switching system which enables the proximity of a finger to be detected. For success with this system, it is necessary to maintain complete electrical isolation between switch areas, and such system has the disadvantage that, when operating in an exposed environment, a water film can bridge switch areas and can thereby cause errors in the detection system.